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中文摘要：
新疆地区广泛应用膜下滴灌技术进行棉花种植,易在膜下浅层根区（0~40 cm）形成淡化区域,而深部根系层（40~60 cm）却始终处于积盐状态,具有较大的积盐和返盐隐患。为了更为便捷地探索节水、高效的暗管排盐模式,在开展蓄水淋洗条件下暗管（埋深60 cm、间距500 cm）排水、排盐田间试验和分析建立相应数值模型的基础上,利用HYDRUS软件和田间试验数据对所建立的数值模型和水盐运动参数进行了校验,结果表明模拟值与实测值之间整体吻合较好,剖面土壤含水量分布的最大均方根差（RMSE）和最小决定系数（R2）分别为0.025 cm~3/cm~3和0.88,含盐量分布的最大RMSE和最小R2分别为2.74 g/kg和0.93,基本在可接受范围之内。尽管剖面土壤脱盐率可达77.5%,但绝大部分盐分都被淋洗至暗管以下土层,暗管排盐量十分有限,仅占60 cm以上土体盐分总量的11.7%,因此有必要探索膜下滴灌棉田暗管排盐的改进模式或方法,以有效提高其排盐效率。本文所建立的数值模型和相关水盐运动参数可以较好地描述暗管排水、排盐过程中的土壤水盐动态,并进一步用于当地膜下滴灌棉田不同暗管排盐模式的数值模拟与分析,从而为新疆膜下滴灌棉田高效排盐模式的探索提供科学依据。
英文摘要：
The technology Xinjiang, China. Salts in low root zone （0~40 em） ondary salinization hazard. of film mulched drip irrigation （FMDI） is applied widely for planting cotton in the soils where FMDI is practiced tend to be leached downwards from the shal- and to accumulate in the lower root zone （40-60 cm） where they become a sec- Numerical simulation should be one of the most effective and rational methods to evaluate the effect of salt discharge by subsurface pipes in the cotton field with FMDI. In this study, a field experiment, in which the leaching water was supplied at the soil surface and the leachate was dis- charged using subsurface pipes （SSPs） located 60 cm below the soil surface in unsaturated soil with an in- terval of 500 era, was conducted in Manas, Xinjiang, and numerical models were established to simulate soil water flow and salt transport under the drainage conditions of SSPs. Results from the field experiment were used to calibrate hydraulic parameters and verify the numerical models using the Hydrus-2D/3D soft- ware package. Simulated and observed soil water content distributions were in good agreement with the maxi- mum root mean squared error （RMSE） and minimum coefficient of determination （R2） of 0.025 em3/cm3 and 0.88, respectively. Correspondingly for soil salinity distributions, the values of maximum RMSE and minimum R2 were 2.74 g/kg and 0.93, respectively. Numerical simulations show that most （77.5%） of the salt in 0-60 cm soil layer was leached downwards, however, limited by the factors such as deep groundwa- ter table and small surface area of the pipe for collecting flow from nearby domain, only about 11.7% of the salt in the 0-60 cm soil layer was discharged via the SSPs. The numerical models and the calibrated soil hydraulic parameters should be useful for further analyzing the dynamics of soil water and salt under the drainage condition of SSPs located in unsaturated soil, and for evaluation of alternative methods for salt leaching and discharge.
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